Bug 19677: Properly escape enumchrom/serialseq data

Bug 19677: Properly escape enumchrom/serialseq data

Some serial issues use angle brackets for denoting certain data.
Currently this is not displayed in Koha. This patch escapes the data so
that angle brackets will display.

To test:
1 - Add an enumchron field to an item containg angle brackets:
"This is a <test>"
2 - View the record in the staff and opac, not the field displays as:
"This is a"
3 - Apply patch
4 - Note full text now displays

Signed-off-by: Charlotte Cordwell <charlotte.cordwell123@gmail.com>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>